Determining The Symptoms Of A Dirty Evaporator Drain Tube
Dirty evaporators display multiple symptoms that indicate that it is dirty and needs to be cleaned. The evaporator is designed to convert warm and often humid air into dry and cooler air. This process removes the heat and humidity by using refrigerant circulating through a series of metallic coils. When this occurs, the humidity is converted to liquid and needs to be removed from the evaporator in order to reduce the build-up of mildew and mold. Noted below are a few of the common warning signs that a problem with the AC evaporator exists and that it needs to be cleaned.
Musty or dirty air coming from the AC vents: When the inside of the evaporator collects bacteria, mold and mildew, residue seeps into the air that it is trying to cool. Once that cool air is circulated through the vents, it is contaminated with bacteria that often cause a musty or dirty smell inside the cabin. For most, this musty and dirty air is more of an annoyance however, for those people who live with Chronic Obstructive Pulmonary Disease or COPD â which includes 25 million people in the United States according the CDC – the bacteria in the air can trigger exasperations or COPD flare-ups, that often cause a hospital visit.
Ready To Schedule Ac Service
We hope youve enjoyed learning a few new things about your AC and feel more prepared to deal with one of the more common problems associated with cooling systemsa clog in the AC drain line.
While you can do a few maintenance tasks and reduce the chance of clogs, your HVAC tech will also inspect the AC drainage line during your annual HVAC maintenance appointment.
Sanitize The Drain Line
After you blow the build-up out of the tee, use water to flush out the condensate line. Take a look at the discharge end of the line on the side of your house. You might be surprised at all of the debris that you blew out of your line.
You should also flush your drain line with vinegar to help break down and remove build-up. Pour a few cups of vinegar down the drain line and let it sit for 20-30 minutes to help break down sludge.
Some folks will tell you that you should pour bleach down your condensate drain. Id advise against thatits usually unnecessary. Bleach also may kill your plants and damage the siding on your home.
Instead, use drain pan tablets to prevent growth in the first place. Drain pan tablets sit inside of your air handlers drain pan and will neutralize organic growth before it starts.
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First How Do You Know The Drain Line Is Clogged
You first need to locate the drain pipe. Usually, its a capped vertical PVC or copper pipe running from your indoor AC unit to the outside of your home near the outdoor unit. Here are common signs of a clogged AC drain pipe:
- Water puddles in your AC’s drain pipe
- Standing water around the unit
- Water damage around the AC unit, fan, or floor
- A full AC condensate pan
- The AC stops running because its water safety switch has automatically shut it off
- Moldy smell throughout the house
How To Clean Or Un

- about how to un-block a clogged A/C or heat pump condensate drain
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
A/C condensate drain de-clog & cleanout: this how-to article explains procedures for cleaning or de-clogging a sluggish, blocked, or leaky air conditioning or heat pump condensate drain.
Condensate drain cleaning and unclogging tools and methods are reviewed, including simple steps that a homeowner can take to clear a blocked condensate drain at little or no cost.
We also provide an ARTICLE INDEX for this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.
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Condensate Drain Blowing Cold Air
Looked at a home built in 2006 with a Goodman Mfg. split system, gas furnace in attic, condenser outside.
The condensate drain line first had an upright piece of PVC, open on top & blowing cold air, then a P-trap. It ended into drain piping under a vanity sink.
Should the upright PVC be capped, or should the P-trap be before the upright PVC?
Thanks,
The P- trap was installed to prevent odors from the vanity drain line, being open will defeat the P-traps intended use, in the winter, the water in the p-trap will evaporate. It never should have been connected to the drain line, it should exit outside.
Actually I was told the p trap is there because the drain is hooked up to a pressurized system. The lack of a cap defeats the design. Cap it.
Actually you both are right
The P- trap was installed to prevent odors from the vanity drain line, being open will defeat the P-traps intended use, in the winter, the water in the p-trap will evaporate. It never should have been connected to the drain line, it should exit outside.
Im not an expert by any stretch of the imagination, but Ive seen the primary drain lines P-trap with and without the cap in place. Obviously if the cap is not there, cold air will blow out of the top . Generally though, Ive seen has the cap in place, not glued.
Ive not taken the time to look this up, so Im flying solo with my memory.
My .02 cents,
I Believe the vents are connected to the sanitary drains???
How Do I Clear A Drain Line Clog
Clearing a drain line requires certain equipment, notably a wet/dry shop vac and possibly an air compressor. If your air handler is located in your attic, it will also require working up there, possibly in a tight space. If youre unable to do this or lack the equipment, you should leave this job up to an HVAC technician — its a quick emergency repair.
If you want to try clearing it yourself, you need to start by locating your air handlers condensate drip pan, which is usually at the bottom of the unit. Carefully slide the pan out and use a wet/dry vac to remove the water. Remove the pan completely and wash it in hot, soapy water to remove any buildup.
Next, try to clear the drain line with suction or positive air pressure. You can try vacuuming the line from either end, but the challenge will be in creating a tight seal around the vacuum hose. You may need to experiment with different attachments or improvise by wrapping a rag around an attachment. Vacuuming will be more effective if you have a partner plug up the other end of the line.
Alternatively, you can use an air compressor to blast air into the air handlers end of the drain tube, in the hopes of blowing the clog out the other end.
Once the drain line is clear, use a funnel to slowly pour a gallon of white vinegar through the tube. This will help kill any remaining mold and algae and can help mitigate the risk of future clogging.
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What Problems Can White Slime Cause
Aside from its revolting appearance, the white slime is not harmfulat first. However, if left unchecked, the slime can cause a blockage in your air conditioners drain line. A clogged drain line prevents the moisture in the drain pan from leaving your home. Instead, it accumulates and eventually overflows.
Some AC systems will shut down automatically before the drain pan spills over. So, you may notice that your AC stops cooling, and your thermostat may display an error message. In other systems, there may be no warning. The overflowing drain pan will cause water damage which can lead to mold growth. Standing water near your AC unit, or a musty smell coming from your vents, may be your first signal that something is wrong.
Signs Of A Clogged Drain Line Or Pan
If youre sure the drain pan or line is clogged, you might want to skip to Clear a Clogged Drain by Hand or Clear a Clogged Drain with Vacuum and Hose.
There are two common signs of a clogged drain line:
The drain pan and drain line are in the bottom of the air handler. As the AC runs, moisture from the air condenses on the indoor coil, runs off the coil into the pan and down the drain.
Debris called sludge can build up in the drain line. Its usually some combination of dust, dirt, mold, algae, hair and fur.
The AC wont start: Many drain pans have a float. If the condensate doesnt drain, the pan will fill up, raise the float and shut down the AC. Its like the float on a dehumidifier.
If your air conditioner wont turn on even though the thermostat is calling for AC, this could be the problem. Our AC Problems Troubleshooting Guide discusses the full range of potential problems to consider.
Leaks: If the area around the air handler or furnace is wet, shut down the system immediately. Not all pans have a float or the float might fail.
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How Do I Suck Out My Ac Drain Line
To clean your AC drain line, you will need a wet/dry vac, a funnel, and a bottle of bleach. First, locate your AC drain line and remove the cap. Next, insert the funnel into the opening and pour a half cup of bleach into the line. Finally, use your wet/dry vac to suck out the bleach and any debris that may be clogging the line.
S To Blow Out Ac Drain
The air conditioner in your home works by cooling and removing moisture from the air inside your home. In order to do this, it uses a condenser to cool the air and a drain to remove the moisture. Over time, the drain can become clogged with dirt and debris, which can cause the air conditioner to stop working properly. To clean the drain, you will need to blow it out with compressed air.Attach the nozzle of the compressed air to the end of the drain line. Turn on the compressor and hold the nozzle about 1 inch from the end of the drain line. Allow the air to flow into the line for about 30 seconds. This will blow out any debris that may be clogging the drain
One of the most important skills that a homeowner can learn is how to blow out their A/C drain. A/C drains can become clogged with dirt, dust, and other debris, which can cause water to back up and overflow into the home. Blowing out the drain helps to prevent this from happening.
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Use Chemical Drain Cleaners
Chemical drain cleaners are another popular way to unclog drains in your home. These chemicals are designed specifically to break down clogs in plumbing systems, so they should be able to do their job well when it comes to unclogging drains in your AC unit. These products usually come in powdered form and need to be mixed with water before being poured down the clogged drain line. They work by breaking down clogs over time, so youll need to leave them in place for several hours.
How To Unclog Your Ac Drain Line

Many people dont know this, but your AC does more than just cool your home. It also removes humidity in your home so that the inside climate is ideal for you to live in. But sometimes, the part of your AC responsible for removing that access humidity gets clogged. Its important to keep this part unclog for reasons beyond dehumidifying your home. A clogged AC condensate drain line may cause condensation to leak and cause water damage. So, what can you do to prevent this?
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Measuring Natural Air Leakage
An air conditioner does two jobs: It cools down the air and it dehumidifies the air. If you live in a dry climate, you dont want the AC to dehumidify much because it uses extra energy and makes you spend more on lip balm and hand lotion. If you live in a humid climate, you really want it to do that second job as well as it can to keep your indoor air dry and comfortable. But where does all that condensate go?
In most homes, it goes outdoors through a pipe, like the one above. Sometimes theres a condensate pump that pumps it out, but most often it drains by gravity alone. Occasionally that condensate line gets clogged. This happened at my condo just as the air conditioning season started cranking up. Gunk in the pipe built up to the point where it was barely draining. We could run the AC for a little while and then wed have to turn it off again as the pipe filled up.
What Causes Drain Lines To Clog
There are multiple reasons why an AC drain line can clog, but living in Florida, its mainly due to humidity. The warm air that blows over the cold evaporator coil on the HVAC unit causes humidity. When condensation travels through the pipe, it creates a perfect environment for algae to accumulate. Central Floridians often keep their AC running 24/7, so its more likely to clog. Algae has been known to cause issues for your AC, so its important to take preventative measures to keep your AC running efficiently.
Another reason AC drain lines clog in Florida is due to rain and storms. Debris from storms can cause leaves and sticks to block your units drain line. With a backup of debris, the AC unit can shut down and negatively affect the system.
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Ac Drainage Line Clog Prevention Tips
We talk a lot about preventative maintenance for HVAC systems. You can do two things to prevent a clogged drain line in your AC.
First, schedule routine maintenance with your HVAC technician. When they service your system, most techs include cleaning the drain line.
If they detect a clog, they’ll blow it out using air pressure. Afterward, your tech should clean and sterilize the drip pan. Then, they can drain the line to ensure you don’t have residual algae.
Second, change your air filter. Such a small thing to do, but a dirty HVAC filter releases a higher amount of dirt and bacteria into your drip pan. This adds to grime buildup and eventually will clog the AC drainage lines.
If you’re now wondering how often you need to change your air filter, there’s a short answer and a long answer.
In short, change the filter when it looks dirty. During the cooling season, you’ll want to check your filter every month or so. You may not need to change it each month, but at least inspect it.
Your HVAC system manufacturer may suggest a different schedule for changing filters. Also, if you smoke, have pets, or suffer from respiratory conditions, you may want to change the filter once a month.
Bonus Tips: How To Prevent A Clogged Ac Drain Line In The Future
To prevent a clogged line going forward, you should:
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What To Do When The Ac Drain Line Is Clogged
An obvious sign of a clogged AC pipe is that the air conditioning system has stopped working. The AC drain line is responsible for removing excess condensation from the unit. Clogged AC drain line can result in flooding around the air handler unit. It can also cause troubles with optimal cooling. A few Bay Areas homeowners complain of a moldy smell around the house because of a build-up somewhere in the system. The air conditioner in this case would still be running, but with a bad odor.
This post will help you understand why drain pipes get clogged and the steps you can do to fix it.
What Clogs an AC Pipe?
Algae is the primary cause of a clogged AC pipe. Drain pipe can get humid because of warm air blowing over the HVAC units cold evaporator coil. It can also result in algae growth. Your air conditioners drain pipe is more likely to clog if it runs constantly. Mold, mildew, and other types of fungi and bacteria growth can also cause issues in the air conditioner.
Unclogging the Air Conditioner Pipe
You should be able to easily fix smaller and regular clogs without any trouble. Dont use bleach to unclog the drain since that can easily damage essential components in the air conditioning system. These are tried and tested steps that can be performed for getting rid of algae, mold and mildew in the air conditioner.
1. Turn Off Power
You need to turn off power to the air conditioner at the breaker and the thermostat.
2. Find the AC Drain Pipe
4. Assess the Blockage
7. Repeat
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